Vaginal self-purification is also known as vaginal self-cleaning. Under physiological conditions, estrogen thickens the vaginal epithelium and enriches it with glycogen, which is broken down into lactic acid by Lactobacillus vaginalis to maintain the normal acidic environment of the vagina and inhibit the growth of other pathogens. Although there are many kinds of bacteria in the normal vagina, they are not pathogenic because of the ecological balance between the vagina and these flora. Estrogen and vaginal pH play an important role in maintaining the ecological balance of the vagina. Among the normal vaginal flora, it can inhibit or kill other bacteria. If the vaginal ecological balance is disrupted or if exogenous pathogens invade, it can lead to inflammation. It is important to avoid frequent vaginal douching to avoid disrupting the normal acidic environment of the vagina thus making it easier for other pathogens to grow.